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Erratic breathing during sleep in heart failure (HF) patients hasbeen observed for centuries, with Cheyne–Stokes respiration (CSR)being the classic example. A rapid increase of knowledge in sleepmedicine over the last few decades has identified a range of sleep-disorderedbreathing conditions, all of which have relevance to thecardiac patient. Sleep-disordered breathing (SDB) is a generic termused to cover the respiratory disturbances during sleep that includeobstructive sleep apnoea (OSA), central sleep apnoea (CSA), CSR/periodic breathing, and obstructive and central hypoventilation. In...

Erratic breathing during sleep in heart failure (HF) patients hasbeen observed for centuries, with Cheyne–Stokes respiration (CSR)being the classic example. A rapid increase of knowledge in sleepmedicine over the last few decades has identified a range of sleep-disorderedbreathing conditions, all of which have relevance to thecardiac patient. Sleep-disordered breathing (SDB) is a generic termused to cover the respiratory disturbances during sleep that includeobstructive sleep apnoea (OSA), central sleep apnoea (CSA), CSR/periodic breathing, and obstructive and central hypoventilation. In adults, an apnoea is defined by 10 s of cessation in airflow; obstructiveapnoeas are accompanied by respiratory effort; and in centralevents, effort is absent. Hypopnoeas are partial events and are variously defined: most definitions include a reduction ofmore than 30% in respiratory airflow or thoracoabdominal excursiontogether with arterial desaturation of 2–4%, or more than 50% reduction in airflow without desaturation. The syndrome of OSA is defined by the presence of more than15 obstructive apnoeas and hyponoeas an hour; or more than 5obstructive apnoeas and hyponoeas an hour associated with symptomssuch as daytime sleepiness and fatigue, nocturnal choking, orunrefreshing sleep. The apnoea–hyponoea index (AHI) is the totalnumber of these events per hour of sleep. Severe SDB is consideredto be present if there are more than 30 apnoea and hyponoeas perhour. The respiratory disturbance index (RDI) is used to expressthe total number of respiratory events per hour of study time andtherefore may differ from the AHI as any episodes of wakefulnessduring the monitoring period will be included in the RDI.